Field of the Invention
Embodiments of the present invention generally relate to a surface pump assembly for transferring fluids into or out of a well or pipeline. Particularly, embodiments of the present invention relate to a horizontal pump assembly having a centrifugal pump connected to a motor.
Description of the Related Art
In oil field applications fluid, like water or oil, is often pressurized and moved either between surface locations or is moved from a surface location to at least one downhole location. For example, there are instances where collected oil must be transported to a remotely located processing facility. In other instances, water is pumped down an injection well for disposal or for maintaining or increasing reservoir pressure in enhanced recovery operations or to encourage the flow of oil in underground formations to another well for recovery. In still other instances, pressurized water is injected into a wellbore to become mixed with oil and bring the oil to the surface of the well where it is separated from the water and collected.
Pumping oil out of a well that does not have adequate natural formation pressure is conventionally done through the use of an electric submersible pump located in the wellbore. The pumps operate at the end of a tubular string and include a pump and an electric motor along with a source of electrical power supplied from the surface to operate the electric motor. Because they operate in fluid at the bottom of a wellbore, electric submersible pumps are necessarily more expensive than conventional surface-mounted pumps. Additionally, repair or replacement of a submersible pump requires the removal of the entire pump assembly.
Multistage centrifugal pumps, which are similar to electrical submersible pumps, have been used at the surface to inject fluid into the wellbore. These surface mounted pumps are generally mounted horizontally with an electric motor and a thrust chamber. One advantage of the surface mounted pump is that the motor is less expensive than a downhole motor and the apparatus can be accessed for repair or replacement without pulling it out of a wellbore.
One problem associated with the surface mounted pump is that the seal between the intake chamber of the pump and the thrust chamber requires repair or replacement due to wear. The repair usually involves removing the entire thrust chamber from the pump. During the repair, the pump will be inoperable. In addition, assembly of the pump is complicated because the pump and the motor must be individually aligned with the thrust chamber.
There is a need, therefore, for an improved surface pump assembly. There is also a need for a horizontal pump having a centrifugal pump connected to a motor without a thrust chamber.